Powder Keg is a rare Artifact card from Urza's Destiny (UDS), collector number 136. Current market price: $70.29 (foil $249.89), TCGplayer market prices via Scryfall.
At the beginning of your upkeep, you may put a fuse counter on this artifact. {T}, Sacrifice this artifact: Destroy each artifact and creature with mana value equal to the number of fuse counters on this artifact.